Apparatus for the dry development of photographic prints



April 3, 1934. F, c, FUKE 1,953,160

APPARATUS FOR THE DRY DEVELOPMENT OF PHOTOGRAPHIC PRINTS Filed March 29, 1930 4 Sheets-Sheet l dbtozueqa F. c. FUKE April 3, 1934.

APPARATUS FOR THE DRY DEVELOPMENT OF PHOTOGRAPHIC PRINTS 1930 4 Sheets-Sheet Filed March 29 April 3, 1934. c, FUKE 1,953,160

APPARATUS FOR THE DRY DEVELOPMENT OF PHOTOGRAPHIC PRINTS 4 Sheets-Sheet 3 Filed March 29 1930 i g (1mm.

April 3, 1934.

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Patented Apr. 3, 1934 APPARATUS FOR THE DRY DEVELOPMENT OF PHOTOGRAPHIC PRINTS Francis Cecil Fuke, East Boldon, England Application March 29, 1930, Serial No. 440,038

Great Britain April 5, 1929 4 Claims. (01. 95-94) The present invention relates to an improved apparatus for the dry development of photographic prints, particularly diazo prints, by means of an alkaline vapor such as ammonia gas.

According to the invention an apparatus for the dry development of photographic prints by the ammonia process, of the .type wherein the prints are passed by continuous bands through a developing chamber, is characterized by a closed developing chamber having the form of a pointed roof in its upper portion and of a pointed trough in its lower portion and by the provision of means for introducing steam into the developing chamber in the form of jets acting upon a continuous band preferably at or near the feeding point of a sheet.

Other features of the improved apparatus will now be described with reference to the accompanying drawings, in which Fig. 1 is an end view of the apparatus, showing the means for producing the mixture of steam and ammonia gas,

Fig. 2 is a cross section on line A--B of Fig. 3,

Fig. 3 is a sectional elevation, some parts being omitted for the sake of clearness,

Fig. 4 is another end view showing the driving gear and means for ventilating the compartment into which the printed sheets are delivered,

Fig. 5 is a detail sectional view of the distributing tube through which steam and ammonia gas are introduced,

Figs. 6 and '7 are respectively a detail sectional view'and an inverted plan showing the means for obtaining anairtight joint at the feeding in and delivery points of the prints,-

Fig. 8 is an elevation and Fig. 9 a corresponding section on line C-Dof Fig. 8 showing in detail a door of the compartment into which the printed sheets are delivered,

Fig. 10 is a sectional elevation and 1 Fig. 11 a detail end view of means for adjustably mounting one of the rollers and of a self-aligning bearing. a

' The apparatus is housed in an outer casing having a front wall 1, a rear wall 2, end walls 3 and 4, bottom 5 and top 6. The front wall 1 is provided with an upper door 7 and a lower door 8 of special constructionhereinafter to be described. The rear wall 2 is provided with an upper screwed onpanel or door 9 and a lower screwed on panel or door 10. The end wall 3 has an upper door 11 compartments l7 and 18 one'at each end of the compartment 16 and divided therefrom by transverse walls 19 and 20. The partitions 19 and 20 extend through the whole width and height of the casing. In the upper part of the main compart-' ment 16 is arranged a developing chamber 21 having two downwardly inclined bottom walls 22 and 23 which together form a pointed trough, a vertical wall 24 parallel to the wall 1 and two upper walls 25 and 26 forming a pointed roof. Owing to this construction the developing chamber is surrounded on all sides by air spaces within the compartment 16 and at the ends by the air spaces within the side compartments 1'7 and 18, whereby an eflicient heat insulation is attained. This is desirable in view of the fact that condensation within the developing chamber is to be avoided or minimized. Within the developing chamber 21 is fixedly mounted upon a rotatable shaft 27, a fabric covered drum 28 with which co-operates an endless band 29 which passes over the feeding-in roller 30, a delivery roller 31 and guide rollers 32, 33 and 34. The band 29 is divided longitudinally into a number of narrow bands for the purpose of preventing creeping, and these individual bands are guided by flanges 35 of the roller 33. The roller 33 is vertically adjustable for the purpose of tightening the band, by means of outwardly extending screw threaded and spring controlled spindles 36. In order to avoid any escape of gas the shaft 37 upon which the roller 33 is fixedly mounted revolves in ball bearings 38 arranged in recesses of slide plates 39 which cover the slots 40 in the wall 19 through which the shaft 37 passes. In order to avoid any jamming of the shaft 37 in case of uneven adjustment of the two spindles 36, the ball bearing is inserted into a housing 41 which has a spherical outer bearing surface 42 and is pivotally mounted in a recess 44 of the slide plate 39 by means of two horizontal pivots 43. The spindles 36 can be adjusted from the outside.

To facilitate the feeding-in of the prints an adjustable platform or table 45 is provided the inner end of which is curved at 46 to co-operate with the feeding-in roller 30 (see Fig. 6). To prevent or minimize the escape of gas, a resilient flap 4'7 of rubber or other suitable material fixed to the wall 1 bears upon the upper surface or the platform across the whole width of the feeding-in slot 48. Tightness of the joint between the inner end of the platform is obtained by -means of-a resilient flap 49 fixed to the platform and bearing against the periphery of the drum 28. A tight joint at the delivery end is obtained by means of a packing flap 50 fixed to a vertlno cally projecting lip 51 of the wall 22 of the developing chamber. 52 is a line approximately indicating the point at and the direction in which the sheet is delivered from the developing chamher into the lower compartment 16 from between the drum 28 and the delivery roller 31.

It may be pointed out that between the packing flaps 49 and 50 there remains a free portion of the periphery of the drum 28 and the roller 31, but escape of gas due to this gap is very slight, as the fabric of the drum and the endless band carry very little gas at this point, having given off practically all the gas during their travel from the feeding-in to the delivery point. Escape of gas between the drum 28 and the wall 19 on the one side and the wall 20 on the other side is, at the gap between the flaps 49 and 50, avoided or minimized by lateral packing strips.

Any condensate formed within the developing chamber will on the one side run down the walls 26 and 23 and collectin the channel formed by the walls 22 and 23 from which it may escape through an opening 55 and pipe '77 to a collecting receptacle '78. On the other side of the machine the condensate will run down the walls 25 and 24 and collect in a channel 54 from which it may pass through a gully 52 into the channel between the lower ends of the walls 22 and 23.

The means for supplying steam and developing gas (such as ammonia gas) is arranged in the lateral compartment 18 and comprises a main receptacle 60 placed at the top of the compartment and provided with a closure 61. This receptacle is filled with the required solution of water and ammonia water, the capacity of the receptacle being preferably sufficiently large to contain one day's supply. The receptacle 60 communicates through a pipe 62 with a float con- .trolled chamber 63 which in turn communicates through a pipe 64 with a feed socket 65 of an electric heater 6'7, the feed socket 65 being provided with a needle or other valve 66 for the purpose of regulating the rate of admission.

The heater may also be provided with a gauge for reading the level of the liquid therein. From the top of the heater 6'7 leads a pipe 68 to the distribution tube '70 inside the developing chamber which extends through the whole length of that chamber and has openings through which the steam and ammonia gas jets issue, preferably against the centres of the bands 29. The steam and gas therefore penetrate the whole thickness of the bands 29 near to the feed-in point of the prints. Two or more holes may be provided in the tube '79 for each band 29 if desired. The tube '70 is" fixedly mounted in the wall 20 as shown in Fig. 5 and a gas tight joint is obtained by means of a packing '73. The other end of the tube is loosely mounted upon the projecting end '75 of a bolt '74 screwed into the opposite wall 19 so that the tube may expand with variation of temperature. At the end of the tube near the wall 19 is provided a drain opening '76 through which condensate formed in the-tube may escape. This condensate passes through the gully 56 into the collecting channel at the bottom'of walls 22 and 23. The holes in the tube '70 increase in size from the point of admission of the steam into the tube towards the end of the tube, Fig. 5 showing the smallest hole '71 and the largest hole '72. In this manner a very uniform distribution of the steam is attained.

The drum 28 and the continuous band 29 are driven from an electric motor 83 arranged in the left hand compartment 17, The motor drives by means of a worm drive 84 and spur gears 85 and 86 the roller 31, and by means of spur gears 98 and 88 the main shaft 27 of the drum 28. The electro-motor 83 also drives by means of a belt drive 91 a fan 90 which draws the mixture of air, gas and steam off from the lower part of the compartment 16 into a discharge tube 91 leading outside the apparatus. In order to avoid any ventilating action of the fan 90 upon the developing chamber an air circulation is provided for by allowing air to enter the compartment 18 at the top through a number of holes and passing from the lower part of the compartment 18 into the lower part of the compartment 16. This air circulation also tends to reduce the temperature in the compartment 18.

In order to avoid any interference with the action of the fan 90 and the circulation of air and gas through the lower part of the compartment 16 under the developing chamber, a door 8 of special construction is provided for removing the prints which collect upon the trough 9'7 at the bottom of the compartment 16. The door comprises (see Figs. 8 and 9) a door frame 92, a fixed door portion 93 adjacent to the hinge, and a slidable door portion 94 adapted to slide in horizontal guide grooves of the door frame. In order to open the door, the door portion 94 is first slid in the grooves 95 until it covers the door portion 93, and the door frame 92 is then, together with the door portions 93 and 94, turned about the hinges 96. In closing the door the frame 93 is first moved into the closing position and the door 94 is then slid into closing position.

The electric circuit of the motor 83 includes a switch 80 and a fuse 82.

The operation is as follows:

The electric heater 6'7 is filled with water, preferably distilled to a predetermined height, the needle valve 66 being closed. The receptacle 60 is filled with a solution of ammonia water and water to suit the type of prints which are to be developed. The solution flows down tube 62 to float chamber 63 which, in known manner, stops the flow when the liquid reaches a predetermined height in the float chamber. Switch '79 is then closed which supplies current to the electric heater. When the water is boiling the needle valve 66 is opened so as to admit the solution of ammonia water and water and the level in the heater is then maintained by the fioat chamber 63. A mixture of steam and ammonia gas passes through tube 68 into the distributing tube '70 and thence escapes through the jet holes and impinges,

suitable adjusting of the current of theelectric heater, the amount of steam and ammonia gas introduced into the developing chamber may be controlled in accordance with the speed of development required. Switch 80 is now closed, and the drum 28 and the bands 29 set in motion. The material to be developed is now laid on table 45 and one edge pushed under the roller 30 which, co-operating with the portion 46 of the table, guides the material on to the drum 28 around which it travels automatically and is expelled at the junction of roller 31 and drum 28 to fall into the lower part of the compartment 16, by which time it is completely developed. Any fumes given ofl? by the developed prints are carried away by the .fan 90 to pipe 91. The prints are removed through the door 8. The table 45 may be adjusted by any suitable means in relation to the.

roller 30 to ensure proper pick-up of the material which is to be developed. The natural elasticity of the elastic strips 49 and 50 maintains their free edges in contact with the drum and bands respectively and prevents escape of gas at the gap necessary between the shelf and drum and between the lip 51 and the bands 29.

By way of example, it may be stated that at an average developing speed, the consumption per hour of liquid ammonia of the density 0.88 is about 2'70 cc. The consumption of additional distilled water 284 cc. with a condensation of 120 cc. These figures can, of course, be reduced and good development still obtained by reducing the speed of the machine. Likewise an increase in the speed of evaporation permits an increase in the developing speed. These figures are; of course, given only by way of example.

I claim:

1. An apparatus for the dry development of photographic prints by the ammonia process comprising a closed developing chamber having the form of a pointed roof in its upper portion and of a pointed trough in its lower portion, an internal drum covered with cloth and an external endless band in contact with the internal drum, one of the rollers over which the external band passes being adjustable from the outside and a perforated tube for simultaneously introducing ammonia gas and steam arranged near the feeding point of the sheet, in such a manner that the ammonia gas and steam jets act upon the rear face of the external endless band.

2. An apparatus for the dry development of photographic prints by the ammonia process comprising a closed developing chamber having the form of a pointed roof in its upper portion and of a pointed trough in its lower portion, an internal drum covered with cloth and an external endless band subdivided transversely into a number of bands one at least of the rollers over which the external band passes being provided with flanges for laterally holding these individual bands and one roller being adjustable from the outside, a perforated tube for simultaneously introducing ammonia gas and steam arranged near the feeding point of the sheet, in such a manner that the ammonia gas and steam jets act upon the rear face of the external endless band.

3. An apparatus for the dry development of photographic prints by the ammonia process comprising a closed developing chamber having the form of a pointed roof in its upper portion and of a pointed trough in its lower portion, an internal drum covered with cloth and an external endless band subdivided transversely into a number of bands one at least of the rollers over which the external band passes being provided with flanges for laterally holding these individual bands and one roller being adjustable from the outside, a tube provided with openings for the issuing steam which increase in size from the point of introduction of the steam into the distributing tube, this'tube being arranged near the feeding point of the sheet, in such a manner that the ammonia gas and steam jets act upon the rear face of the external endless band.

4. An apparatus for the dry development of photographic prints by the ammonia process comprising an internal substantially air-tight developing chamber having the form of a pointed roof in its upper portion and of a pointed trough in its lower portion, two lateral chambers, one on each side of the developing chamber and a chamber arranged below the developing chamber, an internal drum covered with cloth and an external endless band subdivided transversely into a number of bands one at least of the rollers over which the external band passes being provided with flanges for laterally holding these individual bands and one roller being adjustable from the outside, a tube provided with openings for the issuing steam which increase in size from the point of introduction of the steam into the distributing tube further provided with openings for the escape of condensed water, this tube being arranged in such a manner that the ammonia gas and steam jets act upon the rear face of the external endless band, further comprising resilient packing strips, bearing against the external endless band in contact with an internal drum and lateral peripheral strips bearing against the edges of the internal drum.

FRANCIS C. FUKE. 

